Gbindiitg- wheel fob dental purposes



W. W. CURTIS'. GHINDING WHEEL Foa DENTAL PURPOSES.,

APPLICATION FILED MAY 1917.

Patented, May 1 3, 1919,.v

WILLIAM w. CURTIS, or CHICAGO, ILLINOIS.

GRINDING-WHEEL FOR DENTAL PURPOSES.

Specification of Letters Patent.

Patented May 13, 1919.

Application led May 7, 1917. Serial No. 166,793.

To all whom t may concern:

Be it known that I, WILLIAM W. CURTIS, a citizen of the United States, residing at Chicago, in the county of Cook and yState of Illinois, haveinventedcertain new and useful Improvements in Grinding-Wheels for Dental Purposes, of which I do declare the following to be a full, clear, and exact deseription, reference being had to the accompanying drawing, forming a part of this specification.

With grinding wheels for dental purposes, it is of the greatest importance that the peripheries of the wheels shall wear with perfect uniformity in order that the wheels may at all times run absolutely true. Any looseness between the wheel and its spindle or any eccentricity, imperfection or irregularity in the grinding surface of the wheel not only impairs the accuracy of the work, but results in serious discomfort to the patient upon whose teeth the wheels are used. So responsive are the human teeth to the slightest imperfections of the grinding wheel, that defects of a wheel such as are scarcely perceptible to the eye, are instantly noticed when the wheel in operation is brought to bearagainst the teeth. Dental grinding wheels are ordinarily cut or molded in one iece and of the required thickness and wit the desired peripheral contour and then secured to the driving spindle, either detachaloly` by a center screw, or permanently by cementing the wheel to an individual stem or spindle, which may be di`scarded when the wheel is worn out. The method of attaching the wheel by cement to the spindle is preferable because of the rigidity of the connection between the parts. ln practice, it is found, however, that in onepiece dental wheels, whether made from stone or abrasive composition (such as lcarborundum), it is extremely difficult to avoid the presence of slight flaws, imperfections or soft spots which frequently are below the surface and develop only after the wheel has been put to use. Such defects cause the wheel towear irregularly and run out of true and result in great discomfort to the patient even before the defects can be detected by the operator.

Another objection to the present type of one-piece dental grinding wheel is that it is apt to become quickly overheated, requiring its action to be arrested in order that it may be cooled, as by dipping in water.

My present invention has for its object to provide a grinding wheel adapted to be used imperfection iny the composite wheel is avoided, because even if a slight imperfec* tion exists in the grinding surface of one disk, the danger of such imperfection being repeated at the same point in an adjacent disk is so remote as to be negligible. Hence, when a number of these thin disks are grouped and held together upon the spindle, they afford a wearing surface of a` uniform character which is impossible of attainment with a one-piece Wheel. Again, I have found that when thin abrasive disks of such material as carborundum are grouped together, the slight roughness of the material of which they are formed necessarily results in very thin spaces or interstices between the faces of the disks and these thin spaces per mit the access of air and of moisture so that the necessity for such frequent dipping or cooling of the grinding wheel in order to prevent its overheating is avoided.` Even in the absence of any artificial spacing between the disks, their slightly irregular surfaces allow air and moisture to penetrate therebetween,`

so that the disks can be used in the mouth without the necessity of frequent withdrawal and the work of the operator can thus be much more speedily and satisfactorily accomplished. In some instances, in forming my improved composite wheels, l have found it desirable to slightly increase the spaces which, as I have said, exist between the disks even when they are assembled and held together, this being accomplished preferably in the manner hereinafter described.

Figure 1 is a view in elevation of a dental grinding tool embodying my invention. Fig. 2 is an enlarged view showing the central portion of the grinding wheel and the manner of mounting the same on the spindle. Fig. 3 is a view showing a modified way of mounting the wheel upon the spindle. Fig. 4 is an enlarged detail view through the outer portion of one of the wheels. Fig. 5

is a view similar to Fig. 3 but showing space ing disks between the wheels.v Fig. 6 is a.

diameter to be used within the these disks beingordinaril about gli of an inch in thickness and su ciently small in human mouth. applying the disks to the spindle shown in Figs. 1 and 2, the reduced portion a of the spindle is first dipped in a suitable cement and the disks B are then placed successively over the reduced portion a of the spindle, each of the disks .being formed with a central hole corresponding approximately in diameter to the diameter In the manner of of the portion a of the spindle. The'disks will be pressed together as shown in the drawing, but inasmuch as the faces of the disks are rough '0r granular, very slight spaces or interstices b will be formed between the disks B, which spaces, however, will be found of suiiicient width to permit the access of air orl moisture which will materially aid in keeping the disks cool and avoid the necessity of the frequent dipping of the wheel in water for such purpose. As the disks B are successively placed upon the portion a of the spindle, a slight portion of the cement c will pass between the inner portions of the disks, as indicated in Fig. 2 of the drawing, and a film of cement will encircle the portion a of the spindle, as also indicated in Fig. 2. The cement o thus not only serves to hold the disks B together and against relative movement, but also serves to firmly secure the disks to the spindle. When-the disks have thus been placed upon the spindle and the cement is set or hardened, the periphery of the wheel will be ground or trued up so as to give thereto an even and uniform grinding surface,-that is to say, the grinding surface of the finished wheel will betrue and even across the periphery and in this respect will correspond to the grinding surface of the wheels made from a single piece of material, such as stone, carborundum or the like. When the e composite wheel has thus been formed, it will Vbe found that all danger of the wheel wearing eccentrically or irregularly or of any imperfection developing in the grinding surface of the wheel is avoided, because even should an imperfection develop in the periphery of one of the disks, the danger of such imperfection recurring at the corresponding point in an adjacent disk is so s ight as to be negligible. It is obvious that in the manner last described,

instead of placing the disks B separately upon the reduced portion a of the spindle the several disks B may be first cemented to ether and then cemented to the spindle, after which the periphery of the wheel will be trued up in manner last described.

In Fig. 3 of thc drawing, I have shown my improved composite wheel as formed of a plurality of disks B connected to the spindle A by a screw D that enters a threaded socket a2 formed in the end of the spindle. The spindle A has a shoulder a and the screw D has an expanded head ai between which and the shoulder a the composite wheel will be clamped. In this form of my invention, the disks B are first threaded upon the screw D, after which this screw is turned into the threaded socket a2 of the spindle A until the disks are firmly clamped by the head d of the screw against the shoulder portion a of the spindle A.

In the enlarged view Fig. 4 I have endeavored to indicate how it is that the rough or granular faces of the disks B when placed together necessarily leave ve slight spaces or interstices between the dis In Fig. 5 of the drawing, the spindle A has a threaded socket to receive the screw D, as in the construction shown in Fig. 3 of the drawing, and the disks B are clamped between the head d of the screw and the shouldered end a of the spindle, as in the construction shown in Fig. 3, but in this form of my invention, a series of spacing disks F of thin paper or like material are interposed between the abrasive disks B so as to give an increased space between the outer portions of the disks B. If desired, the disks B and the thin spacing disks F may be cemented together before the wheel 1s connected to the splndle by the screw D.

In Fig. 6 ofthe drawing, I have shown my invention as applied to a dental grinding wheel the periphery of which is of somewhat conoidal outline. This wheel is formed of a series. of thin abrasive disks B that are cemented together and to the reduced portion of the spindle in the same manner as are the disks shown in Figs. 1 and 2 f the drawing. After the disks have been placed ulpon the reduced end of the spindle,the peripheral portion of the wheel will be ground down so as to give the wheel the desired shape illustrated in Fig. 6 or whatever special shape may be requlred, it being noted, however, that the peripheral or grinding surface of the wheel is even and uniform so as to present the same effect in this respect as a one-piece wheel.

In practice, I have found that my improved composite wheel formed as above described will wear true and uniformly until the diameter of thewheel is so far reduced as to render its further use impractical and that during such reduction incident to wear, a uniform diameter and even wearing of the grinding surface is maintained. Inasmuch as there is no danger of irregularities or inequality of Wear occurring in the periphery of the wheel, it is found that the operatlon of the wheel upon the teeth of the patient is far less annoying than is the ease with the usual small grinding wheels made from 'a single piece of material, and as I have said, the wheel runs much cooler so that the necessity of its frequent withdrawal from the mouth of the patient in order that the wheel may be dipped in water or may be otherwise cooled is avoided. The air and moisture admitted into the spaces or interstices between the disks much more eiectively serves to cool the disks than is the case With the grinding wheels formed of a single piece of material in which the moisture is on the periphery only of the disk and is speedily thrown therefrom as the Wheel is rapidly revolved. So far as I am aware, my invention resents the rst instance of a dental grin ing wheel formed off a plurality of thin, abrasive disks grouped and secured together and a practical use of this wheel has fully demonstrated the advantages hereinbefore lset forth.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is z- 1. A grinding tool for. dental purposes, comprising the combination with a spindle adapted to be supported by the operators hand, of a composite Wheel of a size adapting it for use in the human mouth, said wheel having an even peripheral grinding surface and being formed of a series of small, thin, carborundum disks each having an unbroken periphery, said disks being secured upon the end of said spindle and `against relative movement and having interstices between them to afford 4access of air and moisture.

2. A grinding tool for dent-al purposes, comprising a composite wheel of a size adapting it for use in the human mouth, said wheel having an even peripheral grinding surface land being formed of a series of small, thin, earborundum disks each having an unbroken periphery, said disks having their axial portions secured together and having interstices between them to afford access of air and moisture.

3. A grinding tool Vfor dental purposes, comprising a spindle and a composite wheel having an even peripheral grinding surface and formed of a series of small, thin, carborundum disks mounted on and cemented to said spindle, each of said disks having. an unbroken periphery and said disks being secured together by intermediate layers of cement.

4. A dental grinding wheel of a size for use in the human mouth and adapted to be mounted u n the end of a hand-supported spindle, sa1d wheel having an even peripheral grinding surface and being formed of a series of small, thin carborundum disks secured together in superposed relation and each having an unbroken periphery.

WILLIAM WV. CURTIS. 

